Modern wireless mobile communication system presents two significant features. The first feature is high-speed broadband. For example, the bandwidth of the fourth generation wireless mobile communication systems may be up to 100 MHz, and the downlink rate may be up to 1 Gbps. The second feature is the mobile Internet, which facilitates mobile surfing on the internet, mobile video on demand, online navigation and other emerging services. The two features put forward higher requirements for wireless mobile communication technologies, such as: ultra-high speed wireless transmission, inter-regional interference suppression, reliable transmission of signals during movement, support for distributed/centralized signal processing, and the like. In the future enhanced fourth generation (4G) and 5th generation (5G) wireless mobile communication systems, the above development requirements need to be satisfied.
In October 2007, the International Telecommunication Union (ITU) approved Worldwide Interoperability for Microwave Access Systems (WiMax) to become the fourth 3G standard. The event is actually a 4G standard battle rehearsal. In fact, in response to the challenges of wireless IP technology flow represented by Wireless LAN and WiMax, from 2005 onwards, the 3GPP organization begins to proceed with a totally new system upgrade, i.e. the standardization work of the Long Term Evolution (LTE) system. It is a quasi-four generations system based on the Orthogonal Frequency Division Multiplexing (OFDM) technology, a first edition of which was launched in early 2009 and gradually started business in 2010 around the world. Meanwhile, the standardization on the fourth generation wireless mobile communication systems (4G, the Fourth Generation) by the 3GPP Organization has also been started in the first half of 2008, which is called Long Term Evolution Advanced (LTE-A). The key standardization of the physical layer process of the system was completed in early 2011. In November 2011, ITU organizations officially announced, in Chongqing, China, that LTE-A system and WiMax systems are two official standards of the 4G systems. Currently, the commercial process of LTE-A system is being gradually expanded worldwide.
In the next decade, for the enhanced fourth-generation wireless mobile communication system, there are generally the following development requirements:                Higher-speed wireless broadband, and focus on optimizing local hotspots in a cell;        Further improvement of the user experience, in particular the need to optimize communication services at the cell boundary area;        The need to continue the researches of new technologies for improving the spectral efficiency, considering that the available spectrum cannot be expanded 1000 times;        High frequency spectrum (5 GHz, or even higher) will be put into use in order to obtain a larger communication bandwidth;        Coordination among existing networks (2G/3G/4G, WLAN, WiMax, etc.) for sharing data traffic;        Specific optimizations for different traffics, applications, and services;        Strengthening the capacity of the system to support large-scale machine communications;        Flexible, intelligent and inexpensive network planning and layout;        Designing schemes for saving the network electricity consumption and the user equipment battery consumption.        
To achieve the above development requirements, the international Third Generation Partnership Project (3GPP) organization, at the 58th plenary meeting, discussed and adopted the device-to-device (D2D) communications technology as a key technology of the enhanced fourth generation wireless mobile communication system.
The D2D technology allows a local communication or peer-to-peer communication without access to the core network. Using a D2D technology transmission, it has a very positive effect in reducing the base station load and extending the battery life of mobile terminal. Typically based on whether there is a macro base station coverage in the scene in which the user equipment (hereinafter referred to as D2D User Equipment) implements the D2D transmission, scenes in which the D2D user equipment is used can be classified as follows: covered by a network, no network coverage, and partially covered by a network, wherein the scene partially covered by a network refers to the case where both D2D user equipment covered by a network and D2D user equipment without network coverage are included.
Currently for D2D communications, in particular the D2D communication within base station coverage, 3GPP defines D2D grant information (Grant). In this grant information, 6 bits will be used for indicating the time-frequency resource positions occupied by D2D PSCCH (Physical Sidelink Control Channel). At present, there is no standardized solution in the prior art for effectively utilizing these 6 bits to indicate the time-frequency resource positions occupied by PSCCH.
Therefore, a solution which can effectively use these 6 bits to inform the UE of the time-frequency resources for the transmission of D2D PSCCH is required.